Antenna compensator



Feb. 6, 1934. c. L. DAVIS ANTENNA COMPENSATOR Filed July 24, 1930 2Sheets-Sheet l INVENTOR.

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ANTENNA COMPENSATOR Filed July 24. 1950 2 Sheets-Sheet 2 I I E;-

g (2/ I 95 Z v INL'EN TOR Patented Feb. 6, 1934 PATEFQT @FTFEQE ANTENNACGMEENSATOB;

Chester L. Davis, Kecinili, Iowa, assigned to Wired Radio, Inc, NewYork, N. Y., a corporation of Delaware Application July 24, 1930. SerialNo. 479,461

7 Claims.

My invention relates broadly to radio signaling systems and moreparticularly to the construction of a device adapted for connection incircuit with an antenna conductor for compenfor the effects oftemperature changes upon such conductor.

One of the objects of my inventi n is to provide a construction ofantenna compensator for maintaining constan frequency operation of an 5antenna conductor independent of changes in temperature conditions.

Another object of my invention is to provide a construction ofcompensator for connection in circuit with an antenna conductor foreffectively compensating changes in length of the antenna conductorunder conditions of variations in temperature.

A further object of my invention is to pro vide a construction ofantenna compensator for correction for variations in frequencycharacteristics of an antenna system for variations in temperatureconditions by arranging thermal expansion means directly adjacent theantenna conductor and subjecting the antenna conductor to changes infrequency characteristics equal and o; Jcsite to normal changes due tovariations in teinperature.

G-ther and further objects of my invention will be understood. from thespecifi ation hereinafter following by reference to the accompanyingdraw ings in which:

Figure 1 is a peepective View of antenna compensator and associatedrigging used in signaling systems; Fig. 2 is a longitudinal sectiontaken through one form of antenna compensator employing the principlesof invention; Fig. 3 is a transverse vertical section taken on line 3-3on Fig. 2; Fig. 4 is a theoretical view illustrating the principlesinvolved in the antenna compensator of my invention, the impedanceelement being shown in elevation; Fig. 5 is a sectional view of amodified form of antenna coinpensator embodying the principles of myinvention with parts shown in elevation; Fig. 6 is a longitudinalcross-sectional View through the antenna compensator with partsillustrated in section 1; Fig. '7 is a cross-sectional View takenthrough the thermostatic control device in the compensator system ofFigs. 5 and 6 on line 7-7 56 of Fig. 6; 8 is a cross-sectional Viewtaken on line 8-8 of Fig. 6; Fig. 9 is a cross-scctional view on line9-9 of 6; and Fig. 10 is a theoretical view illustrating the principleof opera tion of the antenna compensator illustrated in Figs. 5-9.

Referring to the drawings, reference character 1 designates the antennaconductor which is secured to the eyelet member 6 in one end of thecylindrical member in the form illus trated in Fig. 2 this casing may bemade of insulation material. In the modification illustrated in Figs.5-9 the casing may he made of conductive material. lhe rigging for thedevice of my invention as shown in Fig. 1 is such that the compensatoris insulatingly supported by means of insulator 3 respect to halyard aand supporting mast 5. The cylindrical casing 2 is closed at one end bymember '7 which may be screw threaded to engage interior screw threadson the inside walls of casing 2 with pins 0 8 projecting radially intoend of plate '7. The ring member 9 extends through the end plate '7 forsecuring insulator 3 hereto. An insulated support 10 is spaciallymounted by suitable means designated at 11 in a position spaced from theinterior walls of the casing 2. The member 10 is wound by the turns 12of an inductance which is connected at one end with the end of theantenna conductor 1 as indicated at 13. The end 13 of the inductance i2is also 8 connected to the end of the thermometer The inductance 12 istapped along the length thereof to connections which extend into thebore of the thermometer at is, 15, 17, 18, 19, 2o, 21 and 22. Thethermometer is suitably secured to the interior wall 2 and assumes thetemperature of the surrounding atmosphere. In order that the thermometer25 will at all times be retained in its lowest position, I provide aweighted fin 2 on the casing 2 which maintains the casing 2 in apredetermined. position. As changes occur in the length of the antenna 1due to changes in temperature corresponding changes occur in thethermometer 25 and as the mercury therein expands the several taps alongthe inductance 12 are electrically shunted thus serving to reduce theeffective period in proportion to the increase in period of t; e antennaconductor 1. Frequency variations the antenna conductor 1 areaccordingly compensated by frequency variations in inductance 12. Thatis, for changes in frequency characteristics in antenna 1 there areequal and opposite changes frequency characteristics in the inductance12 according to temperature changes. Variations 10s in signalingfrequency are thereby avoided by maintaining an antenna of constantfrequency characteristics independent of temperature changes.

In Figs. 5-9 I have shown a conductive tubu- 11o lar member 26surrounding the inductance 12. Adjacent one end of the tubular member Iarrange a spiral bi-metallic strip 27 having por-- tions 27:: and 27b ofmaterials having different coemcients of expansion. The center of thebimetallic strip 27 is connected to the connecting ring 6 and the end12b of the inductance 12. A strip of insulation 28 is provided on theexterior surface of a number of the convolutions of the bi-metallicstrip 27 preventing electrical shortcircuit with the interior walls ofthe tubular cas ing 26. A guide member 31 in the form of a disc centersthe bi-metallic strip in position and allows the expansion andcontraction thereof. As the temperature increases the bi-metallic stripexpands and moves closer to the interior wall of tubular member 27. Theend of the inductance 12 is connected to the bi-metallic strip 27 asrepresented at 12a. The expansible strip serves as illustrated in Figs.7 and 8, to vary the capacity across the ends of the fixed inductance12. That is as the temperature rises the bi-metallic strip expands andthe capacity increases due to the decrease in spacial relation betweenthe bimetallic strip 27 and the inner walls of the tu bular member 26.The inductance 12 is tl1erefore tuned to a frequency characteristiccompensating for changes in frequency in conductor 1 under conditions oftemperature change. As the temperature decreases the bi-metallic strip27 contracts thereby increasing the effective pacity across theinductance l2 and compensating for the reduction in length of theantenna conductor 1.

While I have described my invention in certain preferred embodiments Idesire that it be understood that modifications may be made and that nolimitations upon my inventions are intended other than are imposed bythe scope oi. the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is as follows:

1. An antenna compensator comprising a suspension member connected withan antenna conductor said suspension member including an inductancedevice electrically connected in series with the antenna conductor andforming an electrical extension thereof and thermoslatic means connectedwith said inductance device for varying the frequency characteristicthereof for compensating for changes in frequency of said antennaconductor under conditions of variable temperature.

2. An antenna compensator comprising a suspension member connected withan antenna conductor said suspension member including an inductancedevice electrically connected in circuit with the antenna conductor, andforming an electrical extension thereof and thermally responsive meansconnected with said inductance device for changing the frequencycharacteristics thereof in an opposite sense to the normal change infrequency characteristics of said antenna conductor under conditions ofvariable temperature.

3. An antenna compensator comprising a suspension member connected withan antenna conductor said suspension member including an inductancedevice electrically connected in series with the antenna wire andforming an electrical extension thereof, a thermally responsive devicecarried by said suspension member and electrically connected with saidinductance device, said thermally responsive device being disposedadjacent said inductance device for changing the capacity across theends thereof and modifying the frequency characteristics of said antennaconductor for compensating for the eifects of temperature changes uponsaid antenna conductor.

4. An antenna compensator comprising a casing member, means at one endof said casing member for suspending said casing member, means at theother end of said casing member for suppo ting an antenna conductor, aweight attached to said casing member for predetermining the positionthereof when in suspension, an inductance device mounted within saidcasing member and electrically connected with said antenna conductor,and a thermostat disposed within said casing member immediately abovethe weighted portion thereof and electrically connected with saidinductance device for predetermining the effective value of inductancein circuit with said antenna conductor.

5. An antenna compensator comprising :1. cas ing member, means at oneend of said casing member for suspending said casing member, means atthe other end of said casing member for supporting an antenna conductor,a weight attached to said casing inen'iber for predetermining; theposition :hereof when in suspension, an inductance device mounted withinsaid casing member and electric-aily cc mooted with said antennaconductor, and a thcrinostatically controlled variable condenserdisposed within said casing member and electrically connected in shuntwith said inductance for pre termining the frequency character of saidinductance in series with antenna conductor in accordance withconditions of temperature.

An antenna compensator comprising a conductive tubular casing,suspension means connected to one end oi said casing, an antennaconductor connecled to the opposite end of said casing, a partitionmember laterally dividing said easing into separate sections, aninductance insu ingly spaced from the interior rails of said casingmember and ii one end electrically connected with said antenna conductorand the other end connected. with said tubular casing in one of thesections th eof, a thermostatically controlled capacity elc nt mountedin the other of the sections 0'" casing member, said capacity elementbeing variable in the spacial relation thereof with respect to theinterior walls of said tubular casing for controlling the frequencycharacteristics of said inductance in series with said antenna conductorin accordance with temperature conditions.

7. An antenna compensator comprising a suspension member, supporting m.ins connected to one end of said suspension rm. nher an antennaconductor connected with other end of said suspension member, aninsulated support extending axially through said casing lllfil'fill'el',an in sula'ed spider disposed between each end of said insulated supportand the interior walls of said casing member, an inductance wound onsaid insulated support and connected one end thereof with said antennaconductor, mercury their-iostat disposed beneath said inductance andwithin said casing member, contacts '1 ranged at spaced intervals alongmercury thermostat and ccnnected with taps on said inductance, and meansfor gravitationally maintaining said thermostat beneath said inductancewhile said Cc sing member is suspended.

CHESTER L. DAVIS.

